Mark Steitle wrote:

I've Attached two pictures of one exhaust port (inside and out) from my
20B.  While looking it over yesterday, I noticed a small (approx. 1/8")
slot along the top of the port.  It has a diverter running lengthwise that
forms the lower lip of the slot.  The slot feeds the EGR system.  My
question is what, if anything, should/could be done with this to improve
power?  It looks nothing like the exhaust port insert in my old (junker)
'89 N/A 13B.

The second picture shows the outside view of the exhaust port, which is a
rather odd shape.  The insert has a passage inside so as to prevent taking
a die grinder and rounding the port.  Is there an improvement waiting to
spring forth here, or should I just leave well enough alone?  Does someone
sell a replacement insert that will give me lots of free hp?  ;-)

Mark S.

We usually block off the EGR else where so the whole EGR system will
pressurize and
there will be little or no net flow. Now in theory it could act as a
helmholzt(s?) resonator
and affect the pressure pulse in the exhaust port but I do not know if
anything
bad is going on becasue of this.

Paul Lamar

I had figured I could block it off by tapping the EGR hole between the EGR
passage and the exhaust port and putting a plug in the hole, or maybe weld
up the slit in the exhaust insert.  Also, what, if anything, should I do
with the 1/8" slit in the exhaust port insert... grind it down... weld it
shut... replace it with a different one?  It appears to be blocking about a
third of the passage.  Does anyone know what type of material the exhaust
port inserts are made from?  Possibly inconnel or 321SS?

Mark S.

No attachment came across Mark.

I think the EGR comes out of a port in one of the intermediate housings.
I know this is the case with the 13B non turbo. Picture below. That is an easy place
to block it off as all you need do is cut out a plate and bolt it down. 

On the turbo version of the 13B center housing this port is missing.
the EGR valve is mounted someplace else.
At least on the 1988 turbo engine I have. Is it missing on the top of the 
center housing on a 20B?

Those port inserts are tough but I don't know what material
they are made from. Could be Inconel or stainless.
They are also tough to get out of there. If you can avoid
messing with them.... by all means avoid it :)

Paul Lamar
 
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